Researchers learn how Ritalin works to calm hyperactivity

 

WASHINGTON (CNN) -- New research shows that drugs commonly taken by children to combat hyperactivity affect two chemicals in the brain. The finding could lead to more effective treatments.

In a study using genetically engineered mice, researchers from Duke University Medical Center found that stimulant drugs used to treat attention deficit disorder, such as Ritalin, Dexedrine and other amphetamines, boost levels of both dopamine, a message-carrying brain chemical associated with activity, and serotonin, associated with a sense of well-being.

The connection between the drugs and dopamine was understood, but the link with serotonin is a new finding. Researchers say a better understanding of how Ritalin and other drugs work could lead to the design of drugs that are more effective but have fewer side effects.

The findings are reported in the latest issue of the journal Science.

Dr. Paul Gainetdinov, one of the Duke researchers, said the findings show that treating hyperactivity may not be a matter of affecting either dopamine or serotonin but of obtaining a proper balance between the two chemicals.

"Hyperactivity may develop when the relationship between dopamine and serotonin is thrown off-balance," he said.

Attention deficit disorder affects between 3 percent and 6 percent of children between ages 4 and 14. Those affected are unsettled, cannot concentrate or sit still and are often disruptive.

The market research firm IMS Health says nearly 14 million prescriptions for stimulants, including Ritalin, were dispensed to children during the last school year, an 81 percent increase from five years earlier.